Work is proposed on the analysis of the patterns of macromolecular biosynthesis in cells infected with reovirus, vaccinia virus and RNA-tumor viruses. Among the projects to be investigated are: attempts to assemble the reovirus transcriptase, reovirus cores and reovirions from their constituent polypeptides; studies on the mechanism that ensures that reovirions contain unique sets of ten distinct RNA segments; studies on the mechanism by which poly A is added to the 3'-termini of mRNA segements; studies of the mode of induction of interferon by UV-irradiated reovirus particles; investigation of the mechanism by which interferon interferes with the multiplication of cells, particularly transformed cells; elucidation of the mechanism by which a subunits of avian RNA tumor virus RNA are converted to b subunits; investigation of the nature of the regulatory mechanisms that specify whether resident RNA tumor virus genes express themselves, using hybridization analysis (with DNA probe to the sarc gene), as well as measurements by means of radioimmunoassays of the amount of virus-coded polypeptides synthesized in a variety of cells and under a variety of conditions; characterization of the changes in macromolecular constitution and topography on cell surfaces that accompany transformation of cells by RNA tumor viruses; and characterization of the three forms of B77 reverse transcriptase (the alpha form, the beta2 form and the alph beta form) in an effort to determine which is the biologically active form. BIBLIOGRAPHIC REFERENCES: Michael E. Wiebe and Wolfgang K. Joklik, The Mechanism of Inhibition of Reovirus Replication by Interferon. Virology 66:229-240 (1975). Hendrik Huismans and Wolfgang K. Joklik, Reovirus-coded Polypeptides in Infected Cells: Isolation of Two Native Monomeric Polypeptides with Affinity for Single-Stranded Virology 70:411-424 (1976).